The present invention relates generally to pumps. More particularly, the present invention relates to self-priming pump systems.
Self-priming pump systems typically include a motor, a main pump having a feeding reservoir, and a vacuum source. The vacuum source is typically fluidly connected to the reservoir, and draws pumped fluid into the reservoir to prime the pump. The reliability of such pumps is often affected by the particular application of use, as well as the environmental conditions. For many applications, the fluid being pumped includes suspended solids such as sand, silt, rocks, rags etc., and may be under a negative, neutral or positive head pressure. In addition, the temperature, humidity and air quality around the pump can vary greatly. Because of these varying applications and conditions, the reliability and maintenance of such self-priming pumps can be less than desirable.
The present invention provides a self-priming pumping system for pumping water, sewage or other pumped material from one location to another. The pumping system preferably includes a motor coupled to a centrifugal pump for driving the centrifugal pump. The pumping system also preferably includes a feeding separator that defines a reservoir that is in fluid communication with the main inlet of the centrifugal pump.
In one illustrative embodiment, a liquid ring vacuum pump is used to prime the pump. The liquid ring vacuum pump preferably includes an inlet that is in fluid communication with the reservoir of the separator. The vacuum pump provides a vacuum to the reservoir, which draws pumped fluid into the reservoir. A float is provided to monitor or detect the fluid level in the reservoir. When the pumped fluid level reaches a desired level, the float may open a valve to let air into the reservoir to maintain the desired level.
The discharge from the vacuum pump is preferably provided to a tank. The tank may be located outside of the reservoir, or preferably within the reservoir. Liquid is collected from the discharge of the vacuum pump by the inner tank, and is provided back to the liquid ring vacuum pump, thereby forming a closed system.
Under neutral or negative head pressure, the vacuum pump causes air to flow from the reservoir into the vacuum pump. It has been found that this airflow, along with vibration or movement of the pump, may cause the pumped fluid inside the reservoir to splash, mist, or otherwise enter the inlet of the vacuum pump. This fluid, which may include sediments or the like, may cause damage to the vacuum pump. In cold weather applications, the fluid may also dilute any antifreeze used in the vacuum pump system, which can reduce the reliability of the system.
To help reduce the possibility that the pumped fluid will enter the vacuum pump system, a deflector may be provided in the reservoir, preferably between the inlet to the vacuum pump and the pumped fluid in the reservoir. This deflector is preferably adapted to deflect or otherwise reduce the possibility that the fluid in the reservoir will enter the inlet of the vacuum pump. Alternatively, or in addition, an extension may be provided on top of the separator. This extension may have a lateral cross-section that is less than the lateral cross-section of the reservoir, but greater than the lateral cross-section of the upper outlet in the reservoir. This extension may increase the distance between the pumped fluid in the reservoir and an upper outlet in the reservoir. Because the distance is increased, the amount of fluid that may splash or otherwise enter the upper outlet, and thus the inlet of the vacuum pump, may be reduced. In addition, because the lateral cross-section is greater than the lateral cross-section of the upper outlet, the extension may help reduce the velocity of the air at the top of the reservoir, which may help reduce the possibility that the fluid will be drawn into the inlet of the vacuum pump. Another approach is to increase the height of the separator itself.
As noted above, the inner tank may receive liquid from the discharge of the vacuum pump, and provides liquid to the liquid ring vacuum pump. To increase the reliability of the liquid ring vacuum pump, the inner tank may be designed to collect sediments in the liquid of the vacuum pump system. For example, the bottom and/or side surfaces of the inner tank may be configured to help collect sediment near a drain port. Alternatively, or in addition, one or more baffles may be provided to help direct or collect the sediment. Once the sediment is collected, a drain port can be opened, and the collected sediment may be removed. In-line filters may also be provided, to help further collect sediment.
Under some conditions, the fluid level in the inner tank may decrease over time. To help maintain a proper fluid level in the inner tank, it is contemplated that the inner tank may be selectively fluidly connected to a fluid source, such as the main pump output. When connected, the fluid source may provide fluid, preferably under pressure, to the inner tank to replenish the fluid in the inner tank. A filter may be provided between the fluid source and the inner tank to help prevent sediment from entering the inner tank.
Under positive head pressure, the fluid level in the reservoir will tend to rise, and in some circumstances, fill the reservoir. To help prevent the pumped fluid in the reservoir from escaping from the reservoir, it is contemplated that the valve that is controlled by the float in the reservoir may be a one-way valve, letting air into the reservoir when the fluid level rises above a desired fluid level, but not letting fluid out of the reservoir. In addition, a valve may be disposed between the upper outlet in the reservoir and the inlet of the vacuum pump. This valve may close when the fluid level in the reservoir reaches some predefined maximum level. Preferably, when the fluid level in the reservoir reaches the predefined maximum level, the valve between the upper outlet in the reservoir and the inlet of the vacuum pump fluidly connects the inlet of the vacuum pump to atmosphere. This may help reduce the load on the vacuum pump.